The present invention relates to the fabrication method, and more particularly, to the machinery, the equipment and the other means required to manufacture a pipeline wall assembly in a continuous, uninterrupted manner, with no joint, from the beginning to the end of the pipeline, with non-metallic materials.
For many centuries, large pipes of considerable length have been constructed and used to transport water. More recently, such large pipes, thousands of miles long, have been constructed to transport oil and natural gas from the point of production to the location where these fuels can be processed or distributed.
These pipelines are usually fabricated with steel tube sections brought to the site and then welded on site. This requires the transport of bulky, heavy and long pipeline sections over long distances and, sometimes, difficult terrain. The assembling, the welding and the inspection, and quality control, of these welds in the field, under difficult conditions, makes the whole operation costly and hazardous. The pipeline usually crosses regions where the climatic conditions may be very severe and vary considerably from season to season. The steel provides the structural strength, but none of the other features that are needed to insure the satisfactory performance of the pipeline and the protection of the steel from ambient conditions and from the corrosive action that the the fluid being transported may have on the steel. Therefore, usually, both inside and especially outside of the pipeline steel shell, layers of insulating and protective materials must be added, thereby increasing the cost and decreasing the reliability, and the lifetime expectancy, of large sections of the completed pipeline.
For several decades, pressure vessels, ducts and/or pipes have been fabricated using nonmetallic filaments or tapes wound around a mandrel and bonded together by a resin system matrix. Upon curing that matrix material and extracting the mandrel, the finished products can compete advantageously with shells made of the best metals. Sections of pipeline so fabricated could be assembled on site to construct the pipeline. However, the joining of various sections on site may again create the problems and difficulties just mentioned in the case of steel sections.
It is therefore desirable to eliminate the need for both transporting pipeline sections and having to assemble them on site. It is preferable to accomplish the overall fabrication task, on site, without structural or temporal interruptions.